An LD for emitting blue light having a short wavelength as a light source capable of high-density read/write of information from/to an optical disk device (such as a CD or DVD), as well as an LD for emitting bluish-purple light (abbreviated as bluish-purple LD hereinafter) for higher read/write density, have been considered promising. In addition, high-speed responsiveness of the bluish-purple LD has been required for further increasing the read/write speed (for example, double speed reading) of the DVD.
Jpn. Pat. Appln. KOKAI Publication No. 2001-10914 discloses a structure having a rich layer abundant in Al or B near the surface of a semiconductor layer continuously from the side face of a striped ridge of a laser element, in order to prevent leakage current and short circuiting of the laser element.
Jpn. Pat. Appln. KOKAI Publication No. 2003-31909 discloses a GaN semiconductor compound laser element having a striped ridge waveguide, wherein a light absorbing region is formed by introducing impurity atoms by ion implantation at a position remote from the region immediately under the ridge in order to prevent an adverse effect due to light leaking from the waveguide region.